Hello, I have Rosewill RFX-120 120mm case fan, which is rated for 87 CFM at 38 dBA max: http://www.rosewill.com/products/s_520/productDetail.htm. I use it for a rear exhaust fan, and it is connected to my motherboard. A few days ago, I stuck a Scythe Ultra Kaze 3k RPM in one of my spare mobo connectors, which made the Rosewill fan stop spinning. After I restarted the computer and replaced everything, I noticed that the fan was quieter and weaker than usual. I connected it directly to the PSU, but with the same results. Speedfan and HardwareMonitor show that the fan is running at 2000 RPM instead of 2200 (+/-10%). A little clarification would be greatly appreciated.
More aboutspinning slower usual
I'm not sure why it did that. Try using an application (like SpeedFan) to check the speed and maybe try to increase the speed.
Also a manual fan controller can also do the trick.